Conventionally, a so-called built-up type XY guide table utilizing a linear guide device has been known as a device for freely moving a work table of a machine tool in the X-direction and the Y-direction, which are orthogonal to each other. More specifically, a rail is arranged on a stationary portion, such as a bed or a column, so as to extend in the X-direction, and a lower table movable along this rail is provided; further, a rail is arranged on this lower table so as to extend in the Y-direction, and an upper table movable along the rail is provided, with the upper table being freely movable in the X-direction and the Y-direction with respect to the stationary portion.
In the XY guide table constructed as described above, a load of a linear guide device supporting movement of the lower table and the upper table is arbitrarily selected, whereby the XY guide table is flexibly applicable to various uses from small load uses to large load uses. Further, through appropriate selection of a length of the rail, it is also possible to elongate a stroke amount of the upper table. However, since the rail in the Y-direction is arranged on the lower table, which is movable in the X-direction, high rigidity is required of the lower table itself; further, the height of the XY guide table as measured from the stationary portion to the upper table cannot but be rather large, resulting in an increase in the size and weight of the XY guide table.
JP 05-18415 A discloses an XY guide table in which a reduction in size and weight is achieved through press working of a thin steel plate. More specifically, end portions of steel plates are bent and raised by press working to thereby form a lower plate and an upper plate of a channel-like configuration; further, there is formed an intermediate plate in which, of its four sides, two opposing sides are bent downwards and remaining two sides are bent upwards, with the upper plate, the intermediate plate, and the lower plate being combined with each other such that the side wall portions formed by bending are opposed to each other. Balls are arranged between the side wall portions opposed to each other, and the balls roll on the side wall portions, whereby the intermediate plate can move in the X-direction with respect to the lower plate, and the upper plate can move freely in the Y-direction with respect to the intermediate plate.
Patent Document: JP 05-18415 A